Here is a comprehensive breakdown of how this exploit vector functions, why it targets AWS environments, and how security engineers can mitigate the risk. Decoding the Vulnerability Payload
callback-url-file:///home/*/.aws/credentials
.aws-2Fcredentials : The URL-encoded path for .aws/credentials , the standard repository for local, hardcoded . The Attack Mechanism
: A callback URL is a URL that an application redirects to after completing a task or process, often used in OAuth flows. The application (client) redirects the user to a server (authorization server), which then redirects back to the client with an authorization code or token via the callback URL.
Connect this to an AWS Lambda function that performs the action (e.g., posting to a database or social media). callback-url-file-3A-2F-2F-2Fhome-2F-2A-2F.aws-2Fcredentials
This string represents a targeted attempt by an attacker to read local AWS credential files from a server's file system. What is file:///home/*/.aws/credentials ?
In OAuth 2.0 and OpenID Connect, the redirect_uri (or callback URL) is a critical security parameter. Many implementations strictly validate that the redirect URI uses HTTPS. However, some custom or legacy implementations may mistakenly allow the file:// scheme. If an attacker can set the redirect URI to file:///home/*/.aws/credentials , the authorization server might attempt to “redirect” by reading a local file and sending its content as the callback payload.
Here, the attacker’s file:///home/*/.aws/credentials becomes glob.glob("/home/*/.aws/credentials") , which matches every user’s credentials file. The attacker gets keys on the system.
: The URI scheme designed to locate files locally on the hosting machine, rather than via http:// or https:// . Here is a comprehensive breakdown of how this
If the application later attempts to that URL (e.g., to verify it’s reachable, to send a test webhook, or to redirect the user), the underlying HTTP client might support the file:// protocol. On many systems, making a request to file:///path reads the local file and returns its contents.
This URI is a attempt using the file:// protocol.
The server-side code, failing to validate the protocol, reads the local file and, in many cases, echoes the content back to the user in the HTTP response. Mitigation Strategies
[profile1] aws_access_key_id = YOUR_ACCESS_KEY_ID_1 aws_secret_access_key = YOUR_SECRET_ACCESS_KEY_1 The application (client) redirects the user to a
: Ensure your application's IAM role has the absolute minimum permissions required. Never run web servers as the 💡 Pro-Tip for Researchers
to trick your application into reading and exfiltrating your AWS configuration file. The Target .aws/credentials
: In modern web development, a callback URL (or redirect URI) is an endpoint where an external service returns data or control to the application after completing a process (such as an OAuth authentication flow).